Synchromesh transmission



Oct. 14, 1947.

i R. s. PLEXICO SYNCHROMESH TRANSMISSION Original Filed Jan. 22, 1945 3Sheets-Sheet l g ww @Z evr /aria) Cd. 14, 1947. 5, PLEIXICO 2,428,892

I smcnnomnsn TRANsMIssIoN Original Filed Jan. 22, 1945 s Sheets-Sheet 2Oct; 14, 1947. R. s. PLEXICO 2,428,392-

SYNCHROMESH TRANSMIS SION Original .Fi led Jan. -22, 1945 3 Sheets-Sheet3 tion for Synchromesh supported by bearings Patented on. 14, 1947Robert s. lle x ico, Royal Oak,

General Motors Corporation, corporation of Delaware miary' 22, 1945,Serial No. I this application April 5,

Original application Ja Divided and 1946, Serial No. 659,120

3 Claims. (61.14-417) This invention relates to a change speedtransmission for vehicles providing four forward speed ratios and onereverse ratio, the shift into each of the three highest ratios beingmade with the aid of synchronizing mechanism.

The object of. the invention is primarily to provide synchromesh forthat driving ratio next above low speed. Other objects are concernedwith novel structure by which the major object is attained and bywhich'also there may be attained other objects and advantages which willbe understood from the descriptionwhich follows:

This application is a division of my applicatransmission, Serial No.573,821, filed January 22,1945. The claims of the parent case relate toa synchronizing device. The claims of this application relate toshifting mechanism. The division is made to comply with an oilicialrequirement.

In the accompanying drawings:

Fig. 1 is a vertical longitudinal section throug the change speedtransmission.

Fig. 2 is a view as seen from line 2-2 of Fig. 1.

Fig. 3 is a section on the broken line 3-3 of Fig. 1.

Fig. 4 is a section as indicated-by line 4-4 of Fig. 3.

Fig. 5 is a view in elevation partly broken away and in section,the'plane of the section being marked 5-! on Fig. 3.

Fig. 6 is aperspective of a detail.

Fig. 7 is a view in elevation partly broken away and in section to showa trap device to collect and retain foreign matter, see line 1-1 on Fig.1.

Fig. 8 is a perspective view of the plate seen in section in Fig. '1.

Referring by reference numerals to the drawing, a clutch shaft II fromthe engine and clutch enters the transmission housing l9 where it is I5.Within the housing, or gear box, shaft ll carries a gear 11, a ring ofclutch teeth I! and it ends in a tapered cone 2|. A synchronizing cone29- with teeth 25 is adapted to rotate on surface 2|.

A transmission shaft 21 extends from a pilot bearing 29 within the endof shaft II to and through bearings II in the rear wall of the gear box.Rigid with shaft 21 is a ring 33 peripherally formed to slidably guide aclutch ring 95. The

'Ringilhasa sively with clutch scribed for the reason tapered surfacesMich, assignor to Detroit, Mich, a

- 2 internal teeth of the ring 35 are to mesh succesteeth 25 and I9.Rotatably mounted on shaft 21 is a gear 91. As in the case of the end ofshaft ll, gear 31 has gear teeth-99, clutch teeth and a tapered end asshown together with a synchronizing cone with clutch teeth. These andother details need not be further dethat no patentable novelty is beingclaimed for this mechanism by itself.

Between the two synchronizing cones and the ring 95 is a spring device4| so positioned that when ring 35 is moved toward the engine end of thegear :box the cone 2! serves to synchronize the rates of rotation sothat shaft 21' may be clutched without noise to rotate jointly withshaft ll.

Gear II on shaft it constantly drives gear 43 keyed to a countershaft 49journaled inthe gear casing walls as shown. A countershaft gear 45 is inconstant mesh with gear teeth 39. When ring 95 is moved rearwardly itlooks gear 31 to. shaft 21 with the aid of'the synchronizing meansdrivesshaft 21 at a speed ratio of less than unity. This may be calledthird speed, fourth speed being the expression used for the direct driveof shaft 21.

The countershaft carries a gear 41 in constant mesh with a gear 49, gear49 with its hub 9| being rotatably supported on shaft 21. Slidable butnon-rotatable on shaft 21 is a gear 53. It has internal teeth adapted toengage external teeth 51 on the hub 5| of gear 49 when moved toward gear49. A synchronizing ring 6! is carried within a forward extension 63 ofgear 53 and retained by a ring 65. There are the usual tapered faces onthe gear extension and ring 9|. plurality of axial extensions 91 shapedas shown by Fig. 2. Gear 49 has apertures 99 one for the passage of eachextension 91. As gear 59 moves forwardly the ring 9| is carried with it;If gears 49 and 59 have unlike rates of rotation the ends of extensions91 engage on one side or the other of the tapered faces 1| leading intothe apertures 99 and resist further movement until the frictionalresistance between the effects synchronization. Then the ends 61 passfreely through the openings 49 and the teeth 55 and I1 engage. Thissecond speed drive is therefore through gear train 11-49 and 41-49 thelatter now locked to shaft 21.

whereby shaft l I Low or first speed is obtained by moving gear 53toward the rear. It carries the synchronized Fla. 4 an as is'held bytongue I29 and rail as device with it, the latter having no function inconnection with lowlspeed. As it moves toward the rear gear 53 slidesinto mesh with countershaft gear I3.

Reverse drive is efiected by a pair of spaced gears I5 and I! on a thirdshaft 18. When'these gears are moved jointly, gear I5 is made to meshwith a countershaft gear "and gear" to mesh with gear 53. Reverse driveis therefore through gear trains II-43. IQ- and IT-53.

The mechanism forshifting the clutches and gears to get the severaldriving ratios is mounted in the cover BI. Into the dome of the coverthere projects a manually operable lever 03 having a fulcrum, not shown.Within the cover are three rods or rails 85, 81, 89. The cover is formedwith regions such as 9! and 93 to guide these rails as they reciprocate.Plugs 95 close openings in the cover through which openings the railsare assembled. This arrangement prevents loss of oil which might occurif the rails were slidably supported in end walls of the-casing. Therails have notches 91 to receive detent balls 99 projecting from coverpockets IOI containing springs I03 to yieldably hold the rails inpositions ofadjustment. Carried by rail 85 is a lever engaging head I05and a fork I01 the lower end of which engages a groove in ring 35. Rail81 carries a second lever engaging head I09 located adjacent head )5.Rail 877 also carries a fork III axially spaced from head I 09 andembracing gear 53.

-Rod 89 carries a head H3 directed laterally over rod 8? and terminatingadjacent head I09. Rod 99 also has a projection H5 operatively engagingthe upper end of a lever I II pivoted to the casing at I i9, its lowerend being received within a collar of shaft "I8 whereby gears 75 and IIare moved. The three heads are notched as at IN to selectively receivethe end of lever 85 as it moves in one plane prior to being moved in asecond plane to reciprocate one or another of the rods and engage theclutches or teeth as described.

The mechanism to prevent the shift of any other than the selected railis a plate I22. It slides along an inner overlying cover surface asshown by Fig. 4. It is guided by pins projecting through slots I23 andI25 of the plate and extending into the cover, the heads I27 serving assupporting means. Tongues I29, I3I are bent down into a plane below theplane of the plate. These tongues are dimensioned to slide into railhead slots I2I. Plat I22 has a transverse slot its for the passage ofthe end of lever 83. Overlying and secured to plate I22 is anothertransversely slotted plate I35. The lever 93 passes through this slot.In one side of the slot of plate I I35 is a bent up tongue I31. In acover opening I39 is slidably mounted a pin "MI backed by a spring I43.In that position of the change speed mechanism wherein the lever is inthe position shown by Fig. 4, the tongue I31 lies closely adjacent theend of pin IIII. When the lever is selectively moved to enter the notchof head I05 it moves parts I35 and I22 with it. Tongue I3I whileremaining in the notch of head II3 also enters the notch of head I09.Tongue I3! therefore holds both rails 89 and 81 when tongue I29 slidesout from the notch of head I05. Then lever 83 may be moved in the slotsof lates I22 and I35 to move rail 85 lengthwise of the transby tongueI3I. Rail 0'! may be moved to obtain second speed or low speed dependinupon its direction of movement. If the lever is moved to engage thenotch of head II3 tongue I29 locks rails and 81. Lest,in the slectingmovement, the lever 83 be moved. beyond the notch of head I09 when ashift to the low or second speed is desired and into head H3 the tonguI3! engaging pin I4I resisted by spring "139 warns the operator of theexcessive lever movement. The broad flat face of projection I31intersecting the motion of pin I gives a steady continuous resistancefeel to the lever 83 when the rail 89 is actually engaged.

. It will be noticed that fork IlI.embraces low speed driving gear 53.The rotation of this gear may tend to rotate fork III and its shaft 81the more especially as some appreciable force is applied by the forkagainst the side of the gear in the act of synchronizing. 1 Any suchrotation might-interfere with a free relationship between the head I09and the interlocking plate. To prevent any rotation of rail 81 the forkIII has a lateral arm I49 forked to straddle rail 89 as best seen inFig. 5. It is also necessary to prevent any axial rotation of rail 89.Fig. 4 shows that the heads I09 and I I3 have extensions with overlyingfaces I45 and M1 so that the non-rotation of rail 8'! ensured asexplained above prevents, by contact of parts of I09 and 3,, anyrotation of rail 89. By this means the correct position of theinterlocking plate I22 and the heads I09 and H3 is effected. Head I05and rail 85 cannot rotate because fork I0! embraces ring 35.

Extending transversely across the gear housing near the bottom thereofis a plate I5I with tongues I53 bent down therefrom. Preferably the endof plate I5! has a part I55 resting on a casing surface and a benttongue I5? which may be welded to a nut I59 engaged by a bolt I6I whichserves to hold a cover I03. The enclosure serves to trap chips andforeign matter driven by the rotating gears through the openings. Aconventional plug I 65 will provide for draining oil and the removal ofsediment. The resiliency of tongue I5I is such that the attachment bythe bolt I6I is sumcient to hold the chip plate in the position shown.

I claim:

1. In a change speed transmission having shift rails, means to selectfrom among said rails and thereafter to shift a selected rail, aninterlocking plate for said rails, means carried by a first rail andstraddling a second rail whereby the first rail is kept from rotation onits axis to maintain the first rail in proper position for engagementwith the interlockin plate.

2. In a change speed transmission having shift rails, means to selectfrom among said rails andthereafter to shift a selected rail, aninterlocking plate for said rails, means carried by a first rail andstraddling a second rail whereby the first rail is kept from rotation onits axis to maintain the first rail in proper position for engagementfrom among said rails and in another plane to move a selected rail, aninterlocking plate moved by said lever tolock two rails in each positionof selection, an abutment carried by said interlocking plate, a springpressed plug carried by said transmission and adapted to be moved bysaid abutment in response to the movement of the lever in the act ofselecting that rail which controls reverse.

ROBERT S. PLEXICO.

REFERENCES CITED 3 The following references are of record in the file ofthis patent:

Number 5 2,320,454 r 1,909,644 2327;550

10 Number UNITED STATES PATENTS Name Date Eberhard June 1, 1943 WescottMay 16, 1933 Peterson et al Aug. 24, 1943 FOREIGN PATENTS Country DateGermany d Apr. 19, 1932

